Southern Mexico, Guatemala (type locality), Costa Rica. Costa Rica: most common in mid-elevation montane wet or moist forest, Atlantic and Pacific slopes.
Wilson (in Brown 1960) made observations on a colony fragment of this species, captured at Pueblo Nuevo, Veracruz, Mexico. He noted that the colonies were polydomous. The fragment he obtained contained workers, eggs (which hatched in the laboratory), and a dealate queen, but the queen was unfertilized and apparently not the colony queen. When he offered the colony fragment a variety of prey types in a "cafeteria" experiment, the foragers mostly recoiled violently. When the ants were cramped together with a 15mm long geophilomorph centipede, they did attack and sting it, finally killing it and dragging it to the brood chamber, where some larvae began to feed upon it. But it was not clear whether this was a typical prey item.
I know this species from Hitoy Cerere at 200m, the north slopes of Volcan Barba from 500-900m, the Penas Blancas Valley from 800-1000m, the San Luis Valley west of Monteverde, Carara Biological Reserve at 500m, and Manuel Antonio National Park near sea level. These are all wet or moist forest sites. modesta inhabits the leaf litter and dead wood on the forest floor. I only know it from Winkler samples of sifted leaf litter, in which I occasionally obtain dealate queens along with workers. Zobeida Fuentes, a Parataxonomist working in the San Luis Valley, found scattered workers in a dead stump, in a patch of mature forest.
Brown, W. L., Jr. 1960. Contributions toward a reclassification of the Formicidae. III. Tribe Amblyoponini (Hymenoptera). Bull. Mus. Comp. Zool. 122:143-230.
Forel, A. 1909. Ameisen aus Guatemala usw., Paraguay und Argentinien (Hym.). Dtsch. Entomol. Z. 1909:239-269.
Found most commonly in these habitats: 65 times found in montane wet forest, 69 times found in mature wet forest, 58 times found in ridgetop cloud forest, 46 times found in tropical rainforest, 43 times found in mesophil forest, 42 times found in tropical moist forest, 33 times found in lowland wet forest, 20 times found in 2º wet forest, 9 times found in wet forest, 7 times found in 2º lowland rainforest, ...
Collected most commonly using these methods or in the following microhabitats: 336 times MiniWinkler, 57 times MaxiWinkler, 22 times Winkler, 11 times Berlese, 6 times search, 10 times Night MiniWinkler, 3 times Baiting, 2 times Mini Winkler, 1 times berlesate, 1 times flight intercept trap
Elevations: collected from 20 - 1840 meters, 630 meters average